The present invention is directed to an improved conditioning valve. Conditioning valves have been developed to simultaneously reduce steam heat and pressure. Conditioning valves eliminate the need for conventional pressure reducing valves and desuperheaters and their separate temperature and pressure measurement-control loops. Typically, conditioning valves are utilized for precise temperature and pressure control in turbine by-pass, drying rolls, air preheater coils, unit tie lines, process reactors, fan drives, compressor drives, plant heating, fuel oil heating, evaporator supply, and atomizing steam.
Steam conditioning valves operate by mixing superheated steam under high pressure with desuperheated steam or atomized water. A problem encountered with prior art valves was that they were complex and difficult to control. An additional problem encountered with prior art conditioning valves was that conditioning occurred in proximity to the valve member. Such conditioning valves required complex structures to provide desuperheating steam or water directly into the valve member, and often failed to achieve uniform distribution of the atomized water or desuperheated steam. Moreover, the greatest area of turbulence often occurs on the outlet side of the valve, downstream of the valve member.
The present invention is directed to a conditioning valve having a smoothly shaped valve housing specifically designed to minimize thermal stresses and fatigue as well as to improve flow characteristics. The smooth flow path shaping avoids flow separation and undesirable vortex streets and therefore maintains a low sound pressure level. The invention incorporates an integral water proportioning system which supplies desuperheating water and which is designed to provide a fixed water to steam flow ratio proportional to the plug position which is a function of the valve stroke. The valve of the present invention is able to respond to large changes in load while maintaining precise temperature control.
The present invention further incorporates novel injection nozzles which uniformly distribute the water within the high turbulence area. The features provided by the nozzles of the present invention assure complete atomization, and thereby optimize evaporation and temperature control. Noise reduction is enhanced by injecting water into the area of highest turbulence.